Canopy assembly for a dual boom drill

ABSTRACT

A portable drilling machine has a forwardly extending horizontal platform upon which is pivotally mounted a pair of spaced forwardly extending frames. The frames are arranged on the horizontal platform to pivot toward and away from each other in a horizontal plane. Each frame carries a boom assembly having front end and rear end portions. The boom assembly front end portion supports a drill unit. The boom assembly is operable to raise the drill unit in a linear vertical path while the frame is arranged to move the boom assembly and the drill unit in a horizontal plane. A canopy assembly having front end and rear end portions is positioned in overlying relationship with the frame and boom assembly and includes a portion covered with an expanded metal screen positioned adjacent the drill unit. The front end portion is pivotally connected to an extensible rod that is concentrically positioned within a lift cylinder rigidly mounted to the frame. Actuation of the lift cylinder extends the rod vertically upwardly to move the front end portion in a vertical plane. The rear end portion is rotatably mounted to the frame and is operable upon actuation of the lift cylinder to move longitudinally in a linear horizontal path on the frame to permit linear vertical movement of the front end portion. With this arrangement, the canopy assembly is moved in a linear vertical path to a preselected height above the portable drilling machine and protects the drill operator during the drilling operation.

United States Patent 1 1 McCormick 1 CANOPY ASSEMBLY FOR A DUAL BOOM DRILL [75] Inventor: Thomas W. McCormick,

Morgantown, W. Va.

[73] Assignee: FMC Corporation, Fairmont, W.

[22] Filed: Jan. 21, 1974 [21] Appl. No.: 435,196

[52] US. Cl. 173/34; 173/37; 173/43; 175/219 [51] Int. Cl. E210 11/02 [58] Field of Search 173/34, 37, 43, 44, 38, 173/23; 299/11; 175/219; 61/45 D [56] References Cited UNITED STATES PATENTS 2,750,155 6/1956 Nixon 175/219 X 2,754,087 7/1956 .lohnson.... 175/219 X 3,283,831 11/1966 Bronder 175/219 X 3,375,880 4/1968 Pyles et al.... 173/37 3,471,888 10/1969 Grant et a1 173/34 X 3,768,574 10/1973 Long 173/38 X 3,784,159 1/1974 Skattman et a1 175/219 X Primary ExaminerDavid H. Brown Attorney, Agent, or FirmStanley J. Price, Jr.

[4 1 July 8,1975

horizontal platform upon which is pivotally mounted a pair of spaced forwardly extending frames. The frames are arranged on the horizontal platform to pivot toward and away from each other in a horizontal plane. Each frame carries a boom assembly having front end and rear end portions. The boom assembly front end portion supports a drill unit. The boom assembly is operable to raise the drill unit in a linear vertical path while the frame is arranged to move the boom assembly and the drill unit in a horizontal plane. A canopy assembly having front end and rear end portions is positioned in overlying relationship with the frame and boom assembly and includes a portion covered with an expanded metal screen positioned adjacent the drill unit. The front end portion is pivotally connected to an extensible rod that is concentrically positioned Within a lift cylinder rigidly mounted to the frame. Actuation of the lift cylinder extends the rod vertically upwardly to move the front end portion in a vertical plane. The rear end portion is rotatably mounted to the frame and is operable upon actuation of the lift cylinder to move longitudinally in a linear horizontal path on the frame to permit linear vertical movement of the front end portion. With this arrangement, the canopy assembly is moved in a linear vertical path to a preselected height above the portable drilling machine and protects the drill operator during the drilling operation. 7

12 Claims, 4 Drawing Figures PATENTED UL 3 SHEET 2 BF 2 CANOPY ASSEMBLY FOR A DUAL BOOM DRILL BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to a canopy assembly for a mobile dual boom drill, and more particularly to a canopy assembly arranged to move in a linear vertical path to a preselected height above a mobile drilling machine to support a section of the mine roof during the drilling operation.

2. Description of the Prior Art In underground mining, conventional roof bolts are employed to support the roof of the mined area. In ad dition. transverse timbers are retained in abutting relation with the roof surface to provide support therefor and are held in place by roof bolts extending through the timbers and engaged engaged the rock strata. The roof bolts extend through predrilled holes in the mine roof and function to prevent sliding movement of the different rock strata relative to each other. The roof bolts stabilize the mine roof condition and reduce the possibility of collapse of a portion of the mine roof resulting in injury to operating personnel and damage to the mining equipment.

Prior to engaging the bolts to the mine roof surface vertical holes must be drilled to a predetermined depth into the roof. U.S. Pat. Nos. 3,319,727 and 3,375,880 disclose portable drilling machines which include a drill unit carried by a boom member that extends forwardly from a mobile car. The boom member is supported by a frame which is pivotally mounted to the horizontal platform of the mobile car. Suitable linkage mechanisms are provided to move the drill unit in a linear vertical path and an angular vertical path. The frame pivotally mounted to the mobile car is provided with a linkage mechanism which permits the frame and the boom to pivot in a horizontal plane while the drill unit traverses a linear path perpendicular to the longitudinal axis of the drilling machine. Further linkage mechanisms are provided to move the drive unit along a linear path in a horizontal plane parallel to the longitudinal axis of the boom. With this arrangement, the drill units are operable to drill bolt holes along lines transverse and parallel to the longitudinal axis of the mobile car.

During the bolt drilling operations and prior to the placement of the roof bolts and transverse timbers to support the roof, the roof is unsupported presenting an unstable condition and a safety hazard to workmen. Consequently, stress present in the overhead strata may result in movement of portions of the roof and a roof fall. There is need for a canopy that is maintained in overlying relationship with the frame and boom of a portable mining machine and may be moved therewith to protect the drill operator during the drilling operations. The canopy assembly must be connected on the frame in such a manner that the canopy is able to move horizontally in a plane parallel to the longitudinal axis of the mobile car. Furthermore, the canopy assembly must be adapted to be movable in a linear vertical path for use in mines having roof portions of different vertical height.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a canopy for a dual boom drill which includes a mobile car having a horizontal platform. A forwardly extending frame is pivotally mounted to the horizontal platform. A boom assembly having front and rear end portions is pivotally secured to the forwardly extending frame to permit movement of drill means supported by the boom assembly front end portion in a vertical plane. A canopy assembly having front and rear end portions is maintained in overlying relationship with the boom assembly. Extensible means are provided for moving the canopy connecting front end portion in a linear vertical plane to a preselected height above the frame. Articulated means are provided for the the canopy assembly rear end portion to the forwardly extending frame. The canopy assembly front end portion is arranged to pivot about the extensible means and move in a linear vertical plane.

The articulating means include a roller rotatably mounted to the upper edge portion of each of the vertical sidewalls of the frame. Channel means retain the roller on the upper edge portion and permit the roller to tranverse a linear horizontal path thereon. The roller is connected to a side arm which projects rearwardly from the rear end portion of the canopy assembly. As the roller traverses the surface of the upper edge portion of the vertical sidewalls, the arm member moves in a path horizontal path parallel to the horizontal plane of the frame.

With the above arrangement actuation of the extensible means to vertically raise the canopy assembly front end portion moves the roller in a linear horizontal path on the upper edge portion. The rectilinear movement of the roller moves the canopy assembly rear end portion connected to the arm member in a horizontal path parallel to the horizontal plane of the frame. The horizontal movement of the rear end portion urges the canopy assembly front end portion to pivot about its connection to the extensible means. Thus, the canopy assembly front end portion is moved in a linear vertical path to engage in abutting relation the mine roof surface or to a position adjacent thereof.

Accordingly, the principal object of this invention is to provide a canopy assembly for a dual boom drill arranged to move in a linear vertical path to a preselected height above the mobile drilling machine to protect the drill operator during drilling operations.

Another object of this invention is to provide a mobile drilling machine with an overhead canopy assembly having a front end portion capable of being raised in a linear vertical path to a preselected height above the mobile drilling machine.

These and other objects and advantages of this invention will be more completely disclosed and described in the following specification, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a mobile drilling machine, illustrating a pair of canopy and drill boom assemblies mounted on the mobile drilling machine.

FIG. 2 is a fragmentary view in side elevation of the canopy assembly illustrating in phantom the linear vertical movement thereof relative to the boom assembly.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2, illustrating the pivotal connection between the front end portion of the canopy assembly and the extensible rod of the canopy cylinder.

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 2, illustrating the articulated connection between the forwardly extending frame and the rear end. portion of the canopy assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and particularly FIGS. 1 and 2, there is illustrated a mobile drilling machine generally designated by the numeral that includes a body portion 12 having a horizontal platform 14 positioned at the front portion thereof. A pair of frames 16 are pivotally mounted to the horizontal platform 14 and extend forwardly therefrom. A boom assembly, generally designated by the numeral 18, includes a front end portion 20 and a rear end portion 22 pivotally secured to the forwardly extending frame 16. The front end portion 20 carries a drill unit 24 having a drill steel mounted therein. A drill bit is secured to the end of the drill steel and a hydraulic motor 26 rotates the drill steel and drill bit.

A canopy assembly, generally designated by the numeral 28, is positioned in overlying relationship with the frame 16 and the boom assembly 18. The canopy assembly 28 includes a front end portion 30 and the rear end portion 32 which is secured to the frame 16 by means described hereinbelow. The front end portion 30 includes a laterally extending side portion 33 positioned adjacent the drill unit 24. An expanded metal screen 34 is secured to the top surface of the side portion 33.

A pair of motors 36 are mounted on the mobile body 12 and activate a pair of hydraulic pumps 38 and a pair of vacuum pumps 40 mounted on the mobile body 12. The drill unit 24 is connected to the vacuum pump 40 by a hose (not shown). A dust collector 42 is secured to each of the frames 16 and is connected by a hose (not shown) to the vacuum pump 40 so that dust generated during the drilling operations is drawn from the bit of the drill unit 24 through a hose to the dust collector 42 by the vacuum pump 40.

Fluid under pressure is supplied by the hydraulic pumps 38 and is fed through lines (not shown) to the hydraulic motors 44 mounted on each side of the mobile body 12. The hydraulic motor 44 is connected by gearing in a speed reducer housing 46 to the sprocket 48. The sprockets 48 carry chains that drive sprockets 50 on the front wheels 52. The front wheels 52 are mounted on shafts 54 suitably secured to the front portion of the mobile body 12 adjacent the horizontal platform 14. The rear wheels 56 are axially supported by the shafts 58 mounted to the rear portion of the mobile body 12. With the above described arrangement. the mobile body 12 carrying the frames 16 and the boom assemblies 18 is propelled along the floor of an underground mine to an area where bolt holes are to be drilled in the mine roof.

As illustrated in FIG. 1, a plurality of parallel spaced channel members 60 are rigidly secured to the platform 14. Each of the channel members 60 extends from the rear end of the platform 14 toward the front end thereof. Rollers of a universl connecting mechanism (not shown) secured to the bottom portion of the frame 16 adjacent the rear end portion 62 thereof are arranged to traverse the channel members 60. Swing means (not shown) mounted on the platform 14 are pivotally connected to the bottom portion of the frame 16. The swing means permit limited lateral swinging motion of the frame 16 relative to the platform 14 while providing continuous support for the frame 16. With this arrangement, the drill unit 24 moves in a horizontal plane perpendicular to the longitudinal axis of the mobile car 12.

A pair of stabilizing jacks 64 are oppositely mounted to the front of the frame 16. The stabilizing jack 64 is actuated either mechanically or hydraulically and includes a base portion 66 arranged to forcibly engage the mine floor 67 and thereby stabilize the frame 16, as illustrated in FIG. 2. The effective length of the jack 64 may be remotely controlled to maintain the frame 16 at an angle to the longitudinal axis of the mobile car 12. A horizontally positioned hydraulic cylinder 68 connects the rear end portion 62 of the frame 16 to a boom carriage 70 which supports the rear end portion 22 of the boom assembly 18 as illustrated in FIG. 1. The boom carriage 70 is suitably supported by the frame 16 and is rotatably mounted thereon. Actuation of the hydraulic cylinder 68 moves the boom carriage 70 longitudinally along the frame 16. The longitudinal movement of the boom carriage 70 relative to the frame 16 moves the drill unit 24 through the boom assembly 18. Thus, the longitudinal range of the drill unit 24 to drill the holes in the mine roof is increased.

An elevating link 71 is supported by the boom carriage 70 and is pinned to a pair of parallel spaced boom arms 74. An elevating mechanism 72 functions to raise and lower the elevating link 72 which, in turn, raises and lowers the boom assembly 18 in an arcuate forward path to thereby move the boom arms 74 longitudinally and provide a resultant rectilinear motion of the drill unit 24 in a linear vertical path. US. Pat. No. 3,375,880 completely describes the arrangement for moving the drill unit 24 in a linear vertical path, as summarized hereinabove.

The canopy assembly 28 has a pair of spaced parallel tubular side members 76 connected by a tubular front member 78 and a tubular back member 80. To provide the canopy assembly 28 with additional structural strength, a transverse member 82 entends between the tubular side members 76. A pair of diagonal members 84 are secured at one end to the tubular side members 76 adjacent the front member 78 and at the other end to the intermediate section of the transverse member 82. The side portion 33 projects outwardly from the canopy assembly front end portion 20 with the frame front member 78 forming a portion of the side portion. The side portion 33 includes a plurality of transverse members 86 and a longitudinal support member 87 that provide strength and rigidity for the canopy side portion 33. The expanded metal screen 34 is secured to the upper surface of the side portion 33 to protect the drill operator from the hazards of rocks dislodging from the mine roof as holes are drilled in the roof.

A canopy lift cylinder 88, illustrated in FlGS. 2 and 3, is mounted by a brace 90 to each of the stabilizing jacks 64 which is, in turn, mounted by a brace 91 to the front of the frame 16. The lift cylinder is positioned in underlying relationship to the tubular side member 76 of the canopy assembly 28. The lift cylinder 88 includes an inner cylinder 92 concentrically positioned therein. The inner cylinder 92 has a vertical chamber 94, and a rod member 96 is slidably positioned in the vertical chamber 94 for extension outwardly therefrom. The canopy lift cylinder 88 can be actuated either manually or hydraulically to extend and retract the rod member 96.

the extension rod 96, as illustrated in FIG. 3, has a transverse bore 98 passing through the upper end portion thereof. A sleeve 100 is concentrically retained in the bore 98. The tubular side member 76 includes a pair of downwardly depending ears 102, each having a transverse bore 104 passing therethrough. The upper end portion of the rod member 96 is pivotally connected to the tubular side member 76 by pin 106 positioned within the bores 104 aligned with the bore 98. A pair of cotter pins 108 retain the pin 106 within the aligned bores 98 and 104 so that the upper end portion of the rod member 96 remains pivotally connected to the tubular side member 76 of the canopy assembly 28.

The rod member 96 includes a plurality of vertically spaced bores 110 that pass transversely therethrough. The inner cylinder 92 is provided with a single bore 112 passing transversely through the upper end portion thereof adjacent the ears 102 of the tubular side member 76. A pin member 114 is arranged to pass through the bore 112 aligned with a selected bore 110 of the rod member 96. The pin 114 connects the rod member 96 to the inner cylinder 92 and thereby maintains the rod member 96 immovable within the vertical chamber 94 of the inner cylinder 92. As illustrated in FIGS. 2 and 3, the rod member 96 is maintained at its lowermost position within the inner cylinder 92. By manually or hydraulically extending the rod member 96 out of the inner cylinder 92 and aligning the bore 112 with a selected bore 110 and passing the pin member 114 therethrough, the rod member 96 can be maintained at a preselected height above the frame 16. As illustrated by the phantom lines in FIG. 2, the adjustable feature of selectively positioning the rod member 96 in the inner cylinder 92 permits raising of the canopy assembly 28 to a desired elevation depending on the height of the mine roof.

The frame 16 includes a pair of oppositely positioned vertical sidewalls 116, one of which is shown in H6. 2. The sidewall 116 is provided with an upper edge portion 118 as illustrated in FIGS. 2 and 4. The edge portion 118 extends horizontally outwardly from the sidewall 116, and gusset 120 maintains the edge portion 118 in a substantially horizontal plane relative to the sidewall 116. A channel member, generally designated by the numeral 122, is positioned on the frame 16 adjacent the canopy assembly tubular member 80.

The channel member 122 includes a lower end portion 124 rigidly secured in abutting relation to the inboard side of the sidewall 116. A horizontally extending lower abutment member 126 of the channel member 122 is secured in abutting relation to the top of the edge portion 1 18. A horizontally extending upper abutment member 128 of the channel member 122 is arranged parallel to the lower abutment member 126 and extends beyond the end of the lower abutment member 126. With this arrangement, the upper and lower abutment members 126 and 128 form an open end portion of the channel member 122 for receiving a roller 130.

The roller 130 is mounted for horizontal, longitudinal movement on the edge portion 118. The upper abutment member 128 projects over a portion of the roller 130 and thereby aids to maintain the roller 130 within the open end portion of the channel member 122 as the canopy assembly 28 is raised and lowered by operation of the lift cylinder 88.

The roller 130 includes a bushing 132 and a threaded shaft member 134 coaxially aligned with the roller 130 projects outwardly from the bushing 132. A pair of par allel spaced arm members 136 suitably secured to the tubular member of the canopy assembly rear end portion 32 project rearwardly therefrom. Each of the arm members 136 includes a bore 138 that passes transversely through the end of the arm member. The shaft member 134 of the roller 130 is arranged to extend through the bore 138 of the arm member 136. A suitable fastening device 140 is threadedly engaged to retain the arm member 136 on the shaft member 134.

The fastening device 140 exerts an inwardly directed force upon the arm member 136 which is transmitted through the arm member to the roller 130. Thus, the roller 130 is urged into abutting contact with the lower abutment member 126. The above described articulated connection between the canopy assembly rear end portion 32 and the frame 16 permits the roller 130 to rotatably traverse the surface of the horizontal edge portion 118 and thereby provide longitudinal movement of the arm member 136 in a horizontal path parallel to the horizontal plane of the frame 16.

The canopy assembly 28 is shown in phantom lines in FIG. 2 at its uppermost elevation. As described hereinabove, the canopy assembly 28 is extended from its lowermost position to a preselected position, within the range of vertical movement of the rod member 96 in the chamber 94, by removing the pin 114 from the aligned bores and 112 of the rod member 96 and the inner cylinder 92. The rod member 96 is then freely movable in the chamber 94 for extension outwardly from the inner cylinder 92. As the rod member 96 moves upwardly in a vertical plane, the roller advances forwardly on the edge portion 118. For an extension of the rod member 96 from its lowermost position to its uppermost position, the axis 142 of the roller 130 traverses the distance 144 on the edge portion 118. Thus, the vertical movement of the rod member 96 in the chamber 94 provides horizontal movement of the roller 130 on the edge portion 118. For a selected position of the rod member 96 intermediate of its upper and lower positions, the axis 142 of the roller 130 will move longitudinally on the edge portion 118 within the distance 144.

The articulation between the roller 130 and the arm member 136 permits the arm member 136 to move in a linear horizontal path parallel to the horizontal plane of the frame 16 as the roller 130 traverses the surface of the edge portion 118. The canopy assembly rear portion 32 connected to the arm member 136 through the back member 80 follows the path traversed by the arm member 136 which is determined by the travel of the rollers 130 on the edge portions 118. The horizontal movement of the arm members 136 and the rear end portion 32 urges the canopy assembly front end portion 30 to pivot about the connection of the ears 106 to the rod members 96. Thus, the combined horizontal movement of the canopy assembly rear end portion 32 and the pivotal movement of the canopy assembly front end portion 30 about the rod member 96 provides a resultant linear vertical movement of the front end portion 30.

The front end section 30, in its lowermost position relative to the frame 16 as illustrated in FIG. 2, is inclined downwardly at an angle from a horizontal plane passing through the pivotal connection of the front end portion 30 to the rod member 96. Extension of the rod member 96 vertically outwardly from the chamber 94,

pivots the front end portion 30 about the pin 106 to approach a substantially horizontal position, as indicated in phantom. With this arrangement, the pivotal movement of the front end portion 30 upwardly in a horizontal plane and the articulation of the rear end portion 32 about the frame 16 in a linear horizontal path moves the front end portion 30 in a linear vertical path as the rod member 96 moves vertically upwardly.

In operation, the mobile drilling machine 10 with the combined boom assemblies 18 and frames 16 extending forwardly from the horizontal platform 14 is moved into position for drilling at a desired area in the mine. The frames 16 are then selectively pivoted toward or away from each other on the horizontal platform 14 to move the respective drill units 24 secured to the ends of boom assemblies 18 into the desired horizontal position. The stabilizing jacks 64 are actuated to urge the base portions 66 into abutting contact with the mine floor 67 to thereby fixedly secure the frames I6. The hydraulic cylinder 68 is actuated to move the boom carriage 70 and the boom assembly 18 longitudinally on the frame I6 while the drill unit 24 is spaced from the roof. The linkage mechanism for the boom assembly 18 is then actuated to move the drill unit 24 vertically upwardly into drilling position. Simultaneously with the vertical movement of the drill unit 24, the canopy assembly front end portion 30 is raised in a linear vertical path by extension of the rod member 96 from the inner cylinder 92 to provide working space from the drill operator beneath the canopy side portion 33.

The canopy front end portion 30 may also be moved into abutting contact with the mine roof surface to thereby support the mine roof during the drilling operation. The drilling operation is then commenced by actuation of the motor 26 to rotate the drill bit. Should rock dislodge from an unsupported section of the mine roof during the drilling operation, the machine operator controlling the drill unit 24 is protected from personal injury by the expanded metal screen 34 covering the side portion 33 of the canopy assembly 28 positioned above him. The covered side portion 33 is conveniently located adjacent the drill unit 24 to permit the operator to position himself below the covered side portion as he controls the drill unit 24.

According to the provisions of the patent statutes, I have explained the principle, preferred construction and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiments. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A canopy for a dual boom drill comprising,

a mobile body having a horizontal platform,

drill means,

a forwardly extending frame pivotally mounted to said horizontal platform,

a boom assembly having front end and rear end portions, said boom assembly rear end portion pivotally secured to said forwardly extending frame to permit movement of said drill means supported by said boom assembly from end portion in a vertical plane,

a canopy assembly having front end and rear end portions maintained in overlying relationship with said forwardly extending frame,

extensible means for moving said canopy assembly front end portion in a linear vertical path to a preselected height above said frame, and

articulating means for connecting said canopy assembly rear end portion to said forwardly extending frame.

2. A canopy for a dual boom drill as set forth in claim 1 which includes,

said articulating means operable to move said canopy assembly rear end portion longitudinally in a horizontal path parallel to the horizontal plane of said forwardly extending frame.

3. A canopy for a dual boom drill as set forth in claim 1 which includes,

said canopy assembly rear end portion movably supported on said forwardly extending frame for longitudinal movement in a horizontal path upon extension of said extensible means.

4. A canopy for a dual boom drill as set forth in claim 1 which includes,

said articulating means operable to move said canopy assembly rear end portion longitudinally in a linear horizontal path parallel to the horizontal plane of said frame and thereby permit said extensible means to move said canopy assembly front end portion in a linear vertical path.

5. A canopy for a dual boom drill as set forth in claim 1 in which,

said canopy assembly front end portion is pivotally connected to said extensible means.

6. A canopy for a dual boom drill as set forth in claim which includes,

said canopy assembly front end portion having an integral laterally extending side portion adjacent said front end portion with an expanded metal screen secured in overlying relation with said side portion adjacent to said drill means.

7. A canopy for a dual boom drill as set forth in claim 1 which includes,

ground stabilizing means for forcibly maintaining said frame immovable relative to said mobile car, said stabilizing means suitably mounted to said frame.

8. A canopy for a dual boom drill as set forth in claim in which,

said frame includes a pair of vertical sidewalls, each of said vertical sidewalls having an upper edge portion,

said articulating means includes a roller positioned for rectilinear rotational movement in a plane parallel to the longitudinal axis of said frame on said upper edge portion,

channel means for maintaining said roller rotatably engaged to said upper edge portion,

a pair of parallel spaced arm members connected to said canopy assembly rear end portion and extending rearwardly therefrom,

a bore extending transversely through each of said arm members,

a shaft member coaxially secured to said roller and projecting outwardly therefrom. said shaft member arranged to extend through said bore, and

fastening means for securing said arm member to said shaft member of said roller.

9. A canopy for a dual boom drill as set forth in claim 1 which includes,

9 10 a pair of forwardly extending frames pivotally said outer cylinder chambers, said inner cylinder mounted in spaced relation to and extending forhaving a chamber therein, wardly from said horizontal platform, a rod member movably positioned in said inner cylinsaid frames pivotally arranged on said horizontal der chamber and having an upper end portion ex platform to move toward and away from each 5 tending outwardly therefrom, and other. and connecting means for pivotally securing said rod said canopy assembly suitably connected to each of member upper end portion to said canopy assemsaid frames so that said canopy assembly pivots in bly front end portion to thereby permit said rod a horizontal plane with said frame. member to move said canopy assembly from end 10. A canopy for a dual boom drill as set forth in 0 portion in a linear vertical path. claim 1 in which, 12. A canopy for a dual boom drill as set forth in said extensible means includes adjustable means for claim 11 which includes,

maintaining said canopy assembly front end pora plurality of vertically spaced bores passing transtion at a preselected vertical height above said versely through said rod member, frame. 15 said inner cylinder having a transverse bore passing 11. A canopy for a dual boom drill as set forth in therethrough, and claim 10 in which said adjustable means includes, a pin member extending through said inner cylinder a pair of outer cylinders mounted in spaced vertical bore aligned with said rod bore to thereby retain relation to said frame, each of said outer cylinders said canopy assembly front end portion at a presehaving a chamber therein, lected vertical height above said frame.

an inner cylinder concentrically arranged in each of 

1. A canopy for a dual boom drill comprising, a mobile body having a horizontal platform, drill means, a forwardly extending frame pivotally mounted to said horizontal platform, a boom assembly having front end and rear end portions, said boom assembly rear end portion pivotally secured to said forwardly extending frame to permit movement of said drill means supported by said boom assembly front end portion in a vertical plane, a canopy assembly having front end and rear end portions maintained in overlying relationship with said forwardly extending frame, extensible means for moving said canopy assembly front end portion in a linear vertical path to a preselected height above said frame, and articulating means for connecting said canopy assembly rear end portion to said forwardly extending frame.
 2. A canopy for a dual boom drill as set forth in claim 1 which includes, said articulating means operable to move said canopy assembly rear end portion longitudinally in a horizontal path parallel to the horizontal plane of said forwardly extending frame.
 3. A canopy for a dual boom drill as set forth in claim 1 which includes, said canopy assembly rear end portion movably supported on said forwardly extending frame for longitudinal movement in a horizontal path upon extension of said extensible means.
 4. A canopy for a dual boom drill as set forth in claim 1 which includes, said articulating means operable to move said canopy assembly rear end portion longitudinally in a linear horizontal path parallel to the horizontal plane of said frame and thereby permit said extensible means to move said canopy assembly front end portion in a linear vertical path.
 5. A canopy for a dual boom drill as set forth in claim 1 in which, said canopy assembly front end portion is pivotally connected to said extensible means.
 6. A canopy for a dual boom drill as set forth in claim 1 which includes, said canopy assembly front end portion having an integral laterally extending side portion adjacent said front end portion with an expanded metal screen secured in overlying relation with said side portion adjacent to said drill means.
 7. A canopy for a dual boom drill as set forth in claim 1 which includes, ground stabilizing means for forcibly maintaining said frame immovable relative to said mobile car, said stabilizing means suitably mounted to said frame.
 8. A canopy for a dual boom drill as set forth In claim 1 in which, said frame includes a pair of vertical sidewalls, each of said vertical sidewalls having an upper edge portion, said articulating means includes a roller positioned for rectilinear rotational movement in a plane parallel to the longitudinal axis of said frame on said upper edge portion, channel means for maintaining said roller rotatably engaged to said upper edge portion, a pair of parallel spaced arm members connected to said canopy assembly rear end portion and extending rearwardly therefrom, a bore extending transversely through each of said arm members, a shaft member coaxially secured to said roller and projecting outwardly therefrom, said shaft member arranged to extend through said bore, and fastening means for securing said arm member to said shaft member of said roller.
 9. A canopy for a dual boom drill as set forth in claim 1 which includes, a pair of forwardly extending frames pivotally mounted in spaced relation to and extending forwardly from said horizontal platform, said frames pivotally arranged on said horizontal platform to move toward and away from each other, and said canopy assembly suitably connected to each of said frames so that said canopy assembly pivots in a horizontal plane with said frame.
 10. A canopy for a dual boom drill as set forth in claim 1 in which, said extensible means includes adjustable means for maintaining said canopy assembly front end portion at a preselected vertical height above said frame.
 11. A canopy for a dual boom drill as set forth in claim 10 in which said adjustable means includes, a pair of outer cylinders mounted in spaced vertical relation to said frame, each of said outer cylinders having a chamber therein, an inner cylinder concentrically arranged in each of said outer cylinder chambers, said inner cylinder having a chamber therein, a rod member movably positioned in said inner cylinder chamber and having an upper end portion extending outwardly therefrom, and connecting means for pivotally securing said rod member upper end portion to said canopy assembly front end portion to thereby permit said rod member to move said canopy assembly front end portion in a linear vertical path.
 12. A canopy for a dual boom drill as set forth in claim 11 which includes, a plurality of vertically spaced bores passing transversely through said rod member, said inner cylinder having a transverse bore passing therethrough, and a pin member extending through said inner cylinder bore aligned with said rod bore to thereby retain said canopy assembly front end portion at a preselected vertical height above said frame. 